[clang-tidy] performance-inefficient-vector-operation: Support proto repeated field

Summary:
Finds calls that add element to protobuf repeated field in a loop
without calling Reserve() before the loop. Calling Reserve() first can avoid
unnecessary memory reallocations.

A new option EnableProto is added to guard this feature.

Patch by Cong Liu!

Reviewers: gribozavr, alexfh, hokein, aaron.ballman

Reviewed By: hokein

Subscribers: lebedev.ri, xazax.hun, Eugene.Zelenko, cfe-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D67135

llvm-svn: 371963

1 files changed, 86 insertions, 2 deletions

diff --git a/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp b/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp
index d5e38eb71f8..ffac24c2b9a 100644
--- a/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp
+++ b/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp
@@ -1,4 +1,7 @@
-// RUN: %check_clang_tidy %s performance-inefficient-vector-operation %t -- -format-style=llvm
+// RUN: %check_clang_tidy %s performance-inefficient-vector-operation %t -- \
+// RUN: -format-style=llvm \
+// RUN: -config='{CheckOptions: \
+// RUN:  [{key: performance-inefficient-vector-operation.EnableProto, value: 1}]}'
 
 namespace std {
 
@@ -62,13 +65,35 @@ class Bar {
 
 int Op(int);
 
+namespace proto2 {
+class MessageLite {};
+class Message : public MessageLite {};
+} // namespace proto2
+
+class FooProto : public proto2::Message {
+ public:
+  int *add_x();  // repeated int x;
+  void add_x(int x);
+  void mutable_x();
+  void mutable_y();
+  int add_z() const; // optional int add_z;
+};
+
+class BarProto : public proto2::Message {
+ public:
+  int *add_x();
+  void add_x(int x);
+  void mutable_x();
+  void mutable_y();
+};
+
 void f(std::vector<int>& t) {
   {
     std::vector<int> v0;
     // CHECK-FIXES: v0.reserve(10);
     for (int i = 0; i < 10; ++i)
       v0.push_back(i);
-      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the vector capacity before the loop
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the container capacity before the loop
   }
   {
     std::vector<int> v1;
@@ -162,6 +187,15 @@ void f(std::vector<int>& t) {
     }
   }
 
+  {
+    FooProto foo;
+    // CHECK-FIXES: foo.mutable_x()->Reserve(5);
+    for (int i = 0; i < 5; i++) {
+      foo.add_x(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'add_x' is called inside a loop; consider pre-allocating the container capacity before the loop
+    }
+  }
+
   // ---- Non-fixed Cases ----
   {
     std::vector<int> z0;
@@ -274,4 +308,54 @@ void f(std::vector<int>& t) {
       z12.push_back(e);
     }
   }
+
+  {
+    FooProto foo;
+    foo.mutable_x();
+    // CHECK-FIXES-NOT: foo.mutable_x()->Reserve(5);
+    for (int i = 0; i < 5; i++) {
+      foo.add_x(i);
+    }
+  }
+  {
+    FooProto foo;
+    // CHECK-FIXES-NOT: foo.mutable_x()->Reserve(5);
+    for (int i = 0; i < 5; i++) {
+      foo.add_x(i);
+      foo.add_x(i);
+    }
+  }
+  {
+    FooProto foo;
+    // CHECK-FIXES-NOT: foo.mutable_x()->Reserve(5);
+    foo.add_x(-1);
+    for (int i = 0; i < 5; i++) {
+      foo.add_x(i);
+    }
+  }
+  {
+    FooProto foo;
+    BarProto bar;
+    bar.mutable_x();
+    // CHECK-FIXES-NOT: foo.mutable_x()->Reserve(5);
+    for (int i = 0; i < 5; i++) {
+      foo.add_x();
+      bar.add_x();
+    }
+  }
+  {
+    FooProto foo;
+    foo.mutable_y();
+    // CHECK-FIXES-NOT: foo.mutable_x()->Reserve(5);
+    for (int i = 0; i < 5; i++) {
+      foo.add_x(i);
+    }
+  }
+  {
+    FooProto foo;
+    // CHECK-FIXES-NOT: foo.mutable_z()->Reserve(5);
+    for (int i = 0; i < 5; i++) {
+      foo.add_z();
+    }
+  }
 }